EP 0791923 A2 19970827 - Method of inhibiting copying of digital data
Title (en)
Method of inhibiting copying of digital data
Title (de)
Verfahren zur Verhinderung des Kopierens von digitalen Daten
Title (fr)
Méthode pour éviter la copie de données numériques
Publication
Application
Priority
US 60669796 A 19960226
Abstract (en)
A method of inhibiting copying of digital data. In a first embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. The sequence of symbols is then encoded by a special encoder that generates special channel bits that don't have a large accumulated digital sum variance. The special channel bits may be unambiguously decoded, but the resulting decoded symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a second embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. The sequence of symbols with one substituted symbol is encoded into channel bits that don't have a large accumulated digital sum variance. The resulting channel bits may be unambiguously decoded but the resulting symbol sequence will be error corrected and the error corrected symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a third embodiment, additional decryption or descrambling information or other data modification information is encoded into the sign of the digital sum variance of each blocked row of data. The decoded additional information is used to decrypt, descramble or otherwise modify the primary information. In an alternative third embodiment, decryption information is encoded into patterns of run lengths. In general, the embodiments and alternatives are independent and can be combined in complex ways to make reencoding difficult.
IPC 1-7
IPC 8 full level
G09C 1/00 (2006.01); G11B 20/00 (2006.01); G11B 20/10 (2006.01); G11B 20/14 (2006.01); G11B 20/18 (2006.01); H03M 5/14 (2006.01); H04L 1/00 (2006.01); H04L 25/49 (2006.01); H04N 5/913 (2006.01); G06F 1/00 (2006.01)
CPC (source: EP US)
G11B 20/00086 (2013.01 - EP US); G11B 20/0021 (2013.01 - EP US); G11B 20/00579 (2013.01 - EP US); G11B 20/00615 (2013.01 - EP US); G11B 20/00688 (2013.01 - EP US); G11B 20/00884 (2013.01 - EP US); G11B 20/00927 (2013.01 - EP US); G11B 20/1426 (2013.01 - EP US); G11B 20/1833 (2013.01 - EP US); H03M 5/145 (2013.01 - EP US); H04L 1/004 (2013.01 - EP US); H04L 25/4906 (2013.01 - EP US); H04N 5/913 (2013.01 - EP US); G06F 2211/007 (2013.01 - EP US); G11B 20/1809 (2013.01 - EP US); G11B 2020/1457 (2013.01 - EP US); G11B 2020/1461 (2013.01 - EP US); G11B 2020/1465 (2013.01 - EP US); G11B 2020/1469 (2013.01 - EP US); H04N 2005/91364 (2013.01 - EP US)
Designated contracting state (EPC)
DE FR GB NL
DOCDB simple family (publication)
US 5699434 A 19971216; EP 0791923 A2 19970827; EP 0791923 A3 20060802; JP H09288864 A 19971104; US 2001028318 A1 20011011; US 5828754 A 19981027; US 6278386 B1 20010821
DOCDB simple family (application)
US 60669796 A 19960226; EP 97101300 A 19970128; JP 2711297 A 19970210; US 13414598 A 19980814; US 85588901 A 20010514; US 88399697 A 19970627